- Find out everything you need to know about fuel economy
- What affects your car's MPG
- Is petrol, diesel or hybrid better for economy?
With the cost of fuel moving steadily upwards, buying a fuel-efficient car must be near the top of everyone’s shopping list. Back in the day, 30 miles per gallon (mpg) was considered good. Now a car isn’t really considered economical if it doesn’t do at least 50 to the gallon.
What is miles per gallon?
Miles per gallon or mpg is how much fuel a car drinks. As it suggests, if you put a gallon of either petrol or diesel in your car, the mpg is the number of miles it would cover before gasping to a halt. The higher the mpg figure, the more fuel-efficient the car is.
What makes a fuel-efficient car?
The amount of fuel a car either sips or gulps is affected by many things. The engine plays a huge part. The size and how efficiently it uses its fuel are crucial, with bigger motors normally swallowing more juice.
As an example, Bentley fuel consumption figures are low, claimed to be 21.6mpg for the Continental GT, because it has a monster 6.0-litre engine. Meanwhile Skoda says their Citigo, with a tiddly 1.0-litre engine, returns 55.4mpg.
Shape and weight are vital too. The more wind-cheating a car’s design is, the less energy will be needed to force it through the air. And the heavier a car is, the more fuel it takes to get it moving and keep things rolling along.
Fuel economy is playing an ever more important role in society with car makers being penalised for producing less fuel-efficient motors. Their answer is to use ever funkier materials and technology in their efforts to shave every gram off the weight of their cars.
What affects a car’s mpg?
How we use our cars is just as important for fuel efficiency as design, size and engine.
Drive a car at low speed around town and it will swallow more fuel – cover fewer miles per gallon – than if you’re cruising along the open road. This is because the engine’s having to use energy constantly stopping and starting.
Road conditions are important too. It takes more fuel to get a car up a hill compared with whizzing down one. And you’ll use more juice if you’re driving into the wind rather than having it blow you along.
How much we use our cars’ features also affects fuel economy. Features such as air conditioning, windscreen wipers and lights all ultimate need power from the engine, and that uses fuel.
Then think about what we do to our cars. Car engineers go to infinite lengths in wind tunnels to make car shapes that slip through the air efficiently. Then all we have to do is put some roof bars on or drive along with the windows open and all that hard work goes to waste. Doing either increases the amount of fuel a car uses.
It’s the same with weight. Car firms invest millions putting cars on extreme diets. Then we drive around with a boot full of heavy work files and mouldy exercise kit and all their efforts are pointless.
Why doesn’t my car’s mpg match the claimed figure?
So that car buyers have some way of comparing how thirsty different cars are, there’s a standard fuel efficiency test that every type of car must go through to be sold. This is called Worldwide Harmonised Light Vehicle Test Procedure (WLTP). As it is laboratory based, without weather and road conditions, figures tend to be much higher than ‘real’ drivers can achieve.
Diesel, petrol or hybrid?
The kind of fuel used by each car has an impact on how fuel-efficient it is. And each type of fuel is suited to a different kind of driving.
As fuels go, diesel has more energy in it than petrol. Diesel cars don’t need to rev as highly and are usually more economical, model for model. But because of the extra exhaust equipment diesel cars need to cut down their poisonous emissions, they’re better for longer journeys.
Hybrid cars, which use a combination of petrol and electric power, are well suited to stop-start motoring. This is thanks to their clever kit that harvests otherwise wasted energy when they slow down and uses it to recharge the batteries.
Petrol is a good combination of the two but well suited to town driving because engines can be noisy at higher speeds. And new technology is enabling ever smaller petrol engines to become ever more powerful, giving petrol a boost in buyers’ eyes at the expense of diesel.
10 brilliantly economical cars
Hyundai Ioniq 1.6GDI Plug-in - 247.8mpg
The way economy is measured gives this plug-in hybrid its astronomical mpg figure.
Toyota Prius Plug-in - 235.4mpg
The Prius comes in both self-charging and the more fuel-efficient plug-in hybrid forms.
Kia Niro Plug-in - 201.8mpg
A high-riding SUV that uses plug-in tech to record impressive fuel efficiency.
Audi A3 e-tron - 166.2mpg
The A3 has a range of economical diesels but none can beat the plug-in hybrid’s mpg.
Volvo XC60 Twin Engine Plug-in - 134.5mpg
Fancy a fuel-sipping, stylish, Swedish SUV? The Volvo’s just the trick with plug-in power.
BMW i8 - 128.4mpg
It might have supercar looks but this plug-in performance car uses clever electric tech.
Peugeot 208 1.6 BlueHDI Allure - 94.2mpg
Britain’s most economical non-hybrid car is stylish, practical and good to drive.
Ford Fiesta 1.5TDCi Style - 88.3mpg
The best-selling car in the UK proves why it’s so popular in its most economical form.
Nissan Micra 1.5dCi Acenta - 88.3mpg
The Nissan has sharp styling and plenty of space as well as being a fuel sipper.
Ford Focus 1.5 Ecoblue - 64.2mpg
The Focus is a popular brilliant-to-drive family hatch with a super-economical diesel engine.
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